1. Field of the Invention
The present invention relates to a wafer transfer apparatus for use in semiconductor processing equipment. The present invention also relates to a substrate transfer apparatus for transferring a substrate in an interface space, which is maintained in a predetermined atmosphere, of a substrate processing equipment.
2. Description of the Related Art
FIG. 13 is a section showing a semiconductor processing equipment 1 of the related art, which is partly cut away. The semiconductor processing equipment 1 is configured to include a wafer processing apparatus 2 and a wafer transfer apparatus 3. The wafer transfer apparatus is an equipment front end module (EFEM). Spaces 9, 10 in the semiconductor processing equipment 1 are filled with a predetermined atmospheric gas, respectively. Specifically, the wafer processing apparatus 2 includes a processing space 10 which is filled with a predetermined atmospheric gas. Similarly, the wafer transfer apparatus 3 includes an interface space 9 which is filled with a predetermined atmospheric gas.
Semiconductor wafers 4, which are contained in each front opening unified pod (FOUP) 5 serving as a substrate container, are each carried into the semiconductor processing equipment 1. The wafer transfer apparatus 3 includes an interface space forming portion 11, FOUP openers 6, and a wafer carrying robot 7. A box 11 defines the interface space 9. The interface space 9 is maintained in a cleaned state due to a dust collecting apparatus, such as a fan filter unit, which is fixed to the box 11 (i.e., interface space forming portion). Each FOUP opener 6 is adapted to open and close doors respectively provided in the FOUP 5 and the interface space forming portion 11. Each FOUP opener 6 can switch a state in which an internal space of each FOUP 5 and the interface space 9 are in communication with each other and a state in which they are closed to each other, by opening and closing each door. A wafer carrying robot 7 is contained in the interface space 9 and is adapted to carry each wafer 4 between each FOUP 5 and the wafer processing apparatus 2.
The wafer carrying robot 7 takes out each unprocessed wafer 4 from each FOUP 5 in a state wherein the FOUP 5 is held by the wafer transfer apparatus 3 and penetration of the outside air into the interface space 9 is prevented. Then, the robot 7 carries the unprocessed wafer 4 taken from the FOUP 5, passes through the interface space 9, and positions the wafer 4 in the processing space 10 of the wafer processing apparatus 2. In addition, the wafer carrying robot 7 takes out each processed wafer 4 from the processing space 10 of the wafer processing apparatus 2. Thereafter, the wafer carrying robot 7 carries the processed wafer 4 taken out from the processing space 10, passes through the interface space 9, and places the wafer 4 again in the internal space of the FOUP 5. By transferring each wafer 4 into the wafer processing apparatus 2 by using each FOUP 5 and the wafer transfer apparatus 3 in this manner, attachment of dust floating in the atmosphere to the wafer 4 to be processed can be prevented. For example, such a technique is disclosed in JP No. 2003-45933 A.
FIG. 14 is a plan view of a semiconductor processing equipment A of a first related art, which is partly cut away. A robot arm 14 of the wafer carrying robot 7 of the first related art includes a first link member 15a which is connected with a base 18 and can be pivoted about a pivot axis A0 set at the base 18, a second link member 15b which is connected with the first link member 15a and can be angularly displaced about a first joint axis A1 set at the first link member 15a, and a third link member 15c which is connected with the second link member 15b and can be angularly displaced about a second joint axis A2 set at the second link member 15b. The third link member 15c has a robot hand 12 provided at its distal end.
The wafer carrying robot 7 is set such that a minimum rotation region 17, which is required for the robot 7 to perform one rotation about the base 18 in a state wherein each link member 15a to 15c is angularly displaced relative to one another to make the smallest form of the robot 7, can be contained in the interface space 9. In other words, a minimum rotation radius R of the robot is set smaller than a half (½) of a length B (FIG. 15) in forward and backward directions of the interface space 9. In addition, a distance L11 between the pivot axis A0 and the first joint axis A1 and a distance L12 between the first joint axis A1 and the second joint axis A2 are set to be the same.
In order to enable the wafer transfer apparatus 3 to perform attaching and detaching operations of each FOUP 5 relative to the wafer transfer apparatus 3 and a transferring operation of each wafer 4 to and from each FOUP 5 held by the wafer transfer apparatus 3, at the same time, there is a case where three or four FOUP openers 6 are provided in the system. In such a case, the wafer carrying robot 7 of the first related art as described above can not reach, in some cases, the FOUP 5 that is farthest from the base 15, by using its hand 12. However, if attempting to extend the length of each link member in order to enlarge a movable region of the robot 7, the robot arm 14 may interfere with the interface space forming portion 11 and may be advanced into a robot invasion restricted region.
FIG. 15 is a plan view showing a semiconductor processing equipment 1B of a second related art, which is partly cut away. As shown in FIG. 15, in the second related art, in order to make it possible to transfer wafers 4 of all of the FOUPs 5, the wafer carrying robot 7 includes a robot main body 13 having a robot arm 14 and a running means 12 which is adapted to drive the robot main body 13 to run in directions Y parallel to the row of the FOUPs 5.
In the second related art, the running means 12 for driving the robot main body 13 to run is located in the interface space 9. The running means 12 can be achieved by employing a direct acting mechanism. It is difficult, however, to seal the direct acting mechanism against dust to be generated in a driving portion, as compared with the case of a rotation driving mechanism. Therefore, due to dust to be generated by the running means, cleanliness in the interface space 9 may tend to be degraded.
In the case of driving the robot main body 13 to run at a high speed, since the robot main body 13 is of a large size, power to be spent for the running operation of the robot main body 13 should be increased, with respect to the running means 12. In addition, the running means 12 should also be of a large size in order to support the robot main body 13, thus making it difficult to downsize the robot 7 and reduce the weight thereof. Because the running means 12 is of a large size, it is difficult to exchange the running means 12 in the case of occurrence of malfunctioning in the running means 12. In addition, the provision of such a running means 12 leads to further increase of the production cost.
Increase of the number of the link members of the robot arm 14 in order to enlarge the movable region of the wafer carrying robot 7 can make the running means 12 as disclosed in the second related art be unnecessary. However, in the case of increasing the number of the link members of the robot arm 14, the robot structure should be complicated so much. Additionally, the increase of the link members increases in turn redundancy of the robot, as such control of the robot arm 14 may tend to be difficult. For example, in regard to the wafer transfer, a teaching operation for teaching transformed states of the robot arm may be further complicated.
Such problems may occur in other apparatuses than the wafer transfer apparatus. Specifically, in the case of substrate transfer apparatuses each provided with a substrate carrying robot for carrying each substrate in the interface space which is maintained in a predetermined atmosphere, the same problems as those describe above may occur.